Emerson Rosemount 3100 Series - Mechanical Installation; Mounting Considerations

Reference Manual
00809-0100-4840, Rev. BA
July 2008
3-3
Rosemount 3100 Series
MECHANICAL
INSTALLATION
Mounting
Considerations
Guidelines:
a) The transmitter should be mounted above the liquid surface using the
2-inch thread provided.
(See “Mounting the Transmitter Above the Liquid Surface“ on page 3-5.)
(See “Accessories for The Rosemount 3101/3102/3105“ on page A-9.)
b) The transmitter should be mounted as near vertical as possible to ensure
a good echo from the liquid surface and maximum echo size received.
The beam angle (to the half-power-point) of the transmitter is 12 degrees
inclusive.
c) Obstructions in the tank, or well, may generate echoes which can be
confused with the real liquid surface echo. Obstructions within the beam
angle generate strong false echoes. Wherever possible, the transmitter
should be positioned to avoid false echoes.
d) To avoid detecting unwanted objects in the tank or well, it is advisable to
maintain a distance of at least 1.3 in. from the center line of the transmitter
for every foot (11 cm per meter) range to the obstruction.
(See Figure 3-1 on page 3-4.)
e) If the transmitter is located near the side of the tank or well, there will be
no false echo generated if the wall is smooth and free of protrusions, but
there will still be a reduction in the echo size. To avoid large echo size
loss, it is recommended that the transmitter not be mounted closer than
12 in. (0,3 m) to the wall.
f) Fatty, dirty, or viscous liquids can cause a “scum line” to build-up on the
tank or well wall. Avoid false echoes by enabling the “scum line
prevention” software feature in a Rosemount 3490 Series Control Unit.
g) If the transmitter is mounted in an enclosed tank, avoid mounting the
transmitter in the center of the tank roof because this could act as a
parabolic reflector and create unwanted echoes. Avoid applications where
heavy condensation could form on the transmitter face.
h) If the transmitter is mounted in a stand-off or nozzle, the transmitter face
should protrude be at least 0.2 in. (5 mm) into the tank. If this is not
possible, see “Mounting the Transmitter Above the Liquid Surface“ on
page 3-5.
i) If the transmitter is used in environments where direct sunlight can cause
very high surface temperatures on exposed instruments, a sun-shade is
recommended.
j) The transmitter will not detect any liquid surface closer than 12 in. (0,3 m)
to the transmitter face.